FRIDAY, April 15, 2011 (HealthDay News) -- Meat and poultry sold in the United States is widely contaminated with drug-resistant strains of Staphylococcus aureus, a bacteria that can cause serious illnesses in humans, a new study contends.
The types of health problems linked to S. aureus range from mild skin infections to life-threatening diseases, such as pneumonia, sepsis and heart infection.
In the new nationwide study, researchers analyzed 136 samples of 80 brands of beef, chicken, pork and turkey purchased at 26 retail stores in five cities: Chicago; Flagstaff, Ariz.; Fort Lauderdale, Fla.; Los Angeles; and Washington, D.C.
The results showed that 47 percent of the samples were contaminated with S. aureus, and that 52 percent of the bacteria were resistant to at least three classes of antibiotics.
DNA testing suggests that the food animals themselves were the major source of contamination with S. aureus, said the researchers at the Translational Genomics Research Institute (TGen) in Phoenix.
The study was published in the April 15 issue of the journal Clinical Infectious Diseases.
"For the first time, we know how much of our meat and poultry is contaminated with antibiotic-resistant Staph, and it is substantial," said study senior author Lance B. Price, director of TGen's Center for Food Microbiology and Environmental Health.
"The fact that drug-resistant S. aureus was so prevalent, and likely came from the food animals themselves, is troubling, and demands attention to how antibiotics are used in food-animal production today," he added.
Current production methods may be to blame, the researchers said, explaining that food animals are crammed into industrial farms and continually fed a low dose of antibiotics. These are "ideal breeding grounds for drug-resistant bacteria that move from animals to humans," the report said.
Exactly what this means in terms of consumer risk is still unclear, experts say.
"Antibiotics are the most important drugs that we have to treat Staph infections; but when Staph are resistant to three, four, five or even nine different antibiotics -- like we saw in this study -- that leaves physicians few options," Price said.
The report authors suggest that the U.S. government routinely survey retail meats and poultry for S. aureus. It already checks for four types of drug-resistant bacteria, the report said.
Staph bacteria can be killed through proper cooking but may still pose a health risk through improper food handling and cross-contamination in the kitchen, the researchers noted.
At a Friday press briefing, Price said: "These findings point to serious problems with the way food animals are raised in the U.S. today. It points directly to problems on the farm.
"The single most effective way to reduce antibiotic-resistant bacteria in food is to stop feeding millions of animals antibiotics," he added.
A group representing the U.S. meat industry took issue with the findings.
In a statement, the American Meat Institute Foundation said that the study's small sample size is "insufficient" to reach the conclusions put forth by the researchers. And the foundation said that, "while the study claims that the many of the bacteria found were antibiotic resistant, it does note that they are not heat resistant. These bacteria are destroyed through normal cooking procedures, which may account for the small percentage of foodborne illnesses linked to these bacteria."
The U.S. Department of Agriculture has more about food safety.